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The Importance of an Air Prep Unit in Dry Sandblasting

  • By QB Technical Support
  • April 10, 2023

Moisture in compressed air

Moisture is an inevitable by-product of the air compression process. The humidity percentage used in weather reports refer to the concentration of water vapor in the ambient air outside and can be as low as 1% and as high as 95%. When air is compressed, it is pressed into a more compact space and becomes hot and contains a higher percentage of vapour. If the air is not cooled before it enters the pot, it will cool down inside the blast pot and hoses (because of the significantly lower ambient air temperature) and the vapour will condense forming water drops.
The moisture can have a devastating impact on the blasting substrate, the protective coating, the efficiency of blasting and on the equipment itself.

Problems in sandblasting using moist air

Moisture in the compressed air can used for sandblasting can have several detrimental and costly effects.

Wastage of abrasive media: To increase the abrasive flow, the operator may choke the pot, increasing the positive pressure inside. This can increases abrasive media consumption by 15%-20%, increased refill time and additional clean up and disposal cost. When using steel grit or steel shot, the need for dry air is even greater as there is potential for the abrasive itself to develop flash rust.

Loss of Efficiency: By choking the pot and reducing the push line pressure, the operator is blasting at reduced pressure. Every 1psi pressure loss, results in 1.5% efficiency loss.

Media Flow: In dry blasting, dry abrasive flows much better than moist abrasive which can clump together and get stuck.

Problems in Surface Preparation: Sandblasting steel removes the protective layer on the metal and makes it susceptible to corrosion. The moisture in the compressed air will result in flash rusting of the surface and reduction in strength of the substrate.

Failure of Protective Coatings applied: Coating manufacturers insist on a rust free surface in order for the coating to adhere to the surface. Failure of the protective coating can result in corrosion of the surface and deterioration of the structure.

Wear and tear of equipment: The sandblasting equipment itself can be damaged through premature wear and tear due to the corrosion from the moisture. It increases the premature wear and tear of the valves, results in downtime and maintenance and repair costs.

What are Air Prep Units?

Air preparation units, also known as air prep units, are specialized devices that are designed to condition and prepare compressed air before it is used in sandblasting equipment. They typically consist of multiple components, including air filters, regulators, and lubricators, which work together to improve the quality of compressed air and regulate its pressure and flow rate.
To ensure optimal performance and efficiency in sandblasting operations, the use of air preparation units, is essential. In this technical blog, we will explore the advantages of using air prep units in the sandblasting process.

Advantages of Using Air Prep Units in Sandblasting

Improved Air Quality: Compressed air used in sandblasting can contain impurities, such as moisture, oil, and dust, which can negatively impact the performance of sandblasting equipment and affect the quality of the finished work piece. Air prep units are equipped with high-quality filters that effectively remove these impurities, ensuring that only clean and dry air is supplied to the sandblasting equipment. This helps prevent clogging of nozzles, reduces abrasive contamination, and results in a higher quality surface finish.

Consistent Pressure Control: Air prep units are equipped with regulators that allow for precise control of the air pressure supplied to the sandblasting equipment. Consistent pressure control is crucial in sandblasting operations as it helps achieve consistent results and prevents damage to delicate or sensitive surfaces. With air prep units, operators can easily adjust and maintain the desired air pressure, ensuring consistent and efficient sandblasting performance.

Extended Equipment Lifespan: The use of air prep units can help prolong the lifespan of sandblasting equipment. By removing moisture, oil, and dust from the compressed air, air prep units prevent these contaminants from entering the sandblasting equipment, which can cause corrosion, wear and tear, and other damages. This helps reduce maintenance costs, downtime, and extends the lifespan of the sandblasting equipment, resulting in increased productivity and cost savings in the long run.
That reduces the reliability and durability of your compressed air equipment and shortens maintenance intervals.

Enhanced Operator Safety: Sandblasting can generate a significant amount of airborne particles and dust, which can be hazardous to the health of operators if inhaled. Air prep units with effective filters can help reduce the concentration of airborne particles and dust in the compressed air, thereby improving the air quality in the sandblasting environment and providing a safer working environment for operators. This is especially important in compliance with workplace safety regulations.

Increased Productivity: The use of air prep units in sandblasting operations can significantly increase productivity. Clean and dry compressed air supplied by air prep units allows sandblasting equipment to operate at optimal performance, minimizing downtime due to clogging or other issues. Consistent pressure control ensures efficient sandblasting, leading to faster and more precise surface preparation. The extended lifespan of equipment also reduces downtime for maintenance and replacement, resulting in higher productivity and cost savings.

Conclusion:

Some blasters think that a moisture separator in place of an air prep unit is adequate but it must be noted that a moisture separator only removes the incoming heavy moisture. Some consider an after-cooled compressor to have the same effect as an air prep unit. But inbuilt aftercooled compressors can lower pressure by 12-14psi (18-21% efficiency loss). Air prep units on the other hand have only a 3psi drop.
Air prep units play a crucial role in enhancing the efficiency and effectiveness of sandblasting operations. They improve the quality of compressed air, regulate air pressure, extend equipment lifespan, enhance operator safety, and increase productivity. Investing in high-quality air prep units is a wise choice for any sandblasting operation, as it can result in improved performance, cost savings, and safer working conditions. So, if you want to optimize your sandblasting process, consider incorporating air prep units into your setup for superior results. Overall, the advantages of using air prep units in the sandblasting process cannot be overstated, making them an essential component in.